Many vinyl compounds are polymerizable by free-radicals. Examples include acrylates and methacrylates, acrylamides and methacrylamides, allyl ethers, and styrenes.
Free-radical polymerization of vinyl compound(s) using certain beta-dicarbonyl (i.e., 1,3-dicarbonyl) compounds in the presence of a peroxide and/or oxygen, a halide salt, and a copper compound such as copper acetylacetonate, has been described in U.S. Pat. No. 3,347,954 (Bredereck et al.). Such compositions cause free-radical polymerization of the vinyl compound(s) over time, with shorter times generally being preferred. Since the compositions are spontaneously reactive, it is common practice to provide them as a two-part system such as, for example, a part A and a part B that are combined immediately prior to use.
Organometallic compounds such as, for example, cobalt and manganese naphthenates and copper acetylacetonate typically have good solubility in many organic systems. However, a typical problem of including such organometallic compounds in curable compositions is that they are prone to color formation, and may not be suitable for use in applications where absence of color is desirable for aesthetic and/or functional reasons.